When a 3D printed component has to be assembled with screws , especially if it's intended to be opened and closed several times during its operational life, the problem of thread durability quickly emerges. The polyamides and polymers used in 3D printing don't, in fact, offer the same threading resistance as metals . A screw inserted directly into the hole of a PA12 component can withstand a few assembly cycles, but after a few tightenings the thread tends to strip, compromising the stability and reliability of the connection. The solution is the threaded insert : a small metal bush installed inside the printed component, which creates a strong, durable thread. The insert makes it possible to apply higher tightening torques and to carry out numerous assembly and disassembly cycles without damaging the part . This guide explains the main types of threaded inserts, the available materials, the criteria for correctly designing the housing hole and the installation techniques in components made through 3D printing .